Friction clutch device



Feb. 23, 1932. H. E. MERRITT FRICTION CLUTCH DEVICE Filed Sept. 16, 1929Patented Feb. 23, 1932' HENRY EDWARD MERRITT, F H'UDDEBSFIELD, ENGLANDFRICTION CLUTCH DEVICE Application filed September 16, 1929, Serial No.393,011, and in Great Britain September 21, 1928.

My invention relates to friction clutch devices, and has for its objectto provide an improved construction or device of this character whichwill be particularly suitable for use in connection with automobiletransmission gear, in order to permit of free-wheeling and of thedis-connection of the gear box to facilitate easy gear changing.

The device is based on the well-known principle of a roller actingbetween two surfaces,

one cylindrical and concentric with the driving and driven shafts andthe other of inclined or cam profile. In one direction of rotation ofone shaft relative to the other the roller automatically disengages andin the other direction it automatically binds the cylindrical andinclined surfaces with a selflocking action in which the frictionalforce is directly proportioned to the torque transmitted.

Clutches of the type referred to, as hitherto usuallyconstructed, sufferfrom the disadvantage that, with the degree of accuracy of manufactureobtainable in commercial 5 production, it is impossible for the load tobe carried equally by all the rollers. As a result the stresses onindividual rollers may be undul high and the locating bearings may be enjected to excessive radial loads. A

further objection is that the clutch cannot easily be locked for bothdirections of rotation, a condition essential for automobiletransmission applications.

The present invention comprises a form of construction or arrangementwhich will overcome the objections mentioned and which will, inaddition, afford an easy means of locking the clutch in both directionswhen desired.

A device according to the present invention is characterized anddifferentiated from the known constructions of friction clutchmechanism, in that the yvedges or cam members are made separately fromand are driven by a suitable cage or claw-shaped driving member securedto the driving shaft. The wedges are, on their inner sides, curved tobear on a central floating ring, and if three of such wedges aredisposed at equal angular intervals all will be constrained to carryequal load and no radial load on the locating bearings is possible. Itis not essential to use only three wedges if great accuracy ofmanufacture is possible, but this number is the only one which ensuresautomatically equal load distribution. The outer faces of the wedges areof inclined or cam formation and between these outer faces and the innercylindrical surface of a drum formed on or secured to the driven shaftthere are disposed rollers, which are located at the appropriate equalangular intervals by means of a cage formed with suitable slots. Thisroller cage is mounted to have permissible limited and controlledangular movement relative to the member driving the wedges.

In order that the device may be usefully employed on a motor vehicle asa free-wheel attachment to permit of coasting, provision is made forinter-connecting means, for controlling movements of the slotted rollercage, so as to connect or dis-connect the driven member to or from thedriving member, with the clutch pedal of a vehicle, whereby ondepression of the clutch pedal there is or may be first produced asynchronizing action on the driven member and later a driving connectionbetween the driven member and the gear box of the vehicle, means beingprovided to enable the driving connection to be maintained when theclutch pedal is raised and to enable it to be released when desired, toreinstitute the free-wheel action. The production of the synchronizingaction mentioned need not, however, necessarily be pro- 85 vided for.

Referring to the accompanying drawings,

Fig. 1 shows a sectional elevation of a device embodying one form of theinvention,

P Fig. 2 is a cross section on the line 2-2,

ig. 1; Fig. 3 is a partial sectional plan view;

Fig. 4 is a sectional end view on the line 44, Fig. 3;

Fig. 5 is a detail showing the means whereby a control member, which maybe connected to the clutch pedal of a vehicle is operative to control aclutch fork which in turn controls the slotted roller cage, and, ifdesired, produces also the synchronizing action on the driven memberprior to connection of the latter to the gear box;

Fig. 6 is a detail showing a modification which may be adopted; and Fig.7 is a fragmentary, sectional detail showing the nature and arrangementof the spring devices.

In the drawings, a represents a driving shaft connected say to the gearbox of a vehicle, and b a member fast thereon and having threeprojections 12 with parallel slots between them. In these slots areplaced three Wedges 0, the hardened and ground camshaped outer surfacesof which engage with rollers (1, carried in a cage 6 which is concentricwith the claw member I). The rollers are adapted to be wedged by theaction of the transmitted torque between the wedge pieces 0 and thehardened and ground inner surface of a drum f, formed on or carried by adriven shaft 9. The inner surfaces of the wedge pieces 0 are curved toan appropriate radius to seat themselves upon a central floating annularring it, a certain amount of radial clearance being provided which istaken up by flat springs z' disposed in grooves j in the wedge piecesand in the floating ring h.

The operation of the rollers and wedges is as follows I When torque isapplied to the claw member I), the pressure between the wedges, rollersand annulus f, occasioned by the springs 2' causes the rollers to rollup the cam surfaces of the wedges and produce a self-locking action. Therollers are constrained to retain their equally-spaced position by meansof the cage 6 and to maintain equilibrium of the floating ring it everyroller must carry the same load.

A ring member 7c, slidable on the hub of the claw member 6, has a seriesof projections or fingers which are adapted to enter recesses e in theroller cage 0 and, when so positioned, to limit the rotary movement ofthe cage in the direction which would carry the rollers into thereverse-drive position. When the projections or fingers 7c arewithdrawn, the cage is free to move and the rollers and wedges will bindin either direction of rotation of the driving member a. The cagelocking ring is has an annular groove 70 in which engages a clutch forkm carried by a boss m slidable on a fixed spindle n. coiled spring 0confined in a recess in the boss m of the clutch fork tends to move thecage locking ring to locking position, and a cam p adapted to bearagainst a roller m on the boss m (see Fig. 5) enables the locking ringto be moved to inoperative position. A synchronizing ring 1" encirclingand carried by the cage locking ring, is adapted to engage a surface fon the driven drum f when the locking ring has been moved fully intooperative position.

The cam p is carried by a spindle s which is operatively connected bysuitable means,

not shown, with a control member which may be the clutch pedal of thevehicle, and the said cam is so shaped that when the clutch pedal israised a part 32' of the cam engages the roller m and holds the clutchfork in a position in which the fingers 7c are engaged in the recessesof the roller cage and hold the latter locked in the free-wheelposition, the synchronizer ring 1" being at such time held clear of theco-operating surface 7 on the drum 7. When the clutch pedal is depressedthe cam first presents a concavity 39 into which the roller can move,and the spring 0 operates to bring the synchronizer ring into action,reducing thereby the speed of the driven member to that of the drivingmember, that is to say to the speed for the time being transmitted fromthe gear box. Further depression of the clutch pedal causes a part ofthe cam to engage the roller m and to move the clutch fork to a positionin which the fingers 7c are withdrawn clear of the recesses in theroller cage, the synchronizer ring being, of course, withdrawn as theclutch fork commences its withdrawing movement. Driving connection isthereby established between the driving and driven members, and as thisconnection is established when the engine clutch is disconnected, theshock of engagement is reduced to a minimum.

In order to maintain the driving connection when the clutch pedal israised again, a non-return catch t operated by a spring at is providedto engage a projection '21 on the clutch fork boss, and a Bowden cableor like connection '20 is provided to enable the catch to be released.At any time, therefore, after driving connection has been established asabove described, the free-wheel can be brought into operation byreleasing the catch and permitting the spring 0 to move the looking ringis into operative position.

The means above described thus enable a driving connection to beestablished at will, the speed of the driven member to be reduced tothat of the driving member; the driving and driven members to berotatively connected when desired; and re-introduction of free-wheelaction to be effected by operation of a Bowden cable or equivalentconnection. At any engine speed the engine can be used as a brake, andthis is effected solely through the action of the clutch pedal.

In an alternative arrangement the depression of the clutch pedal,instead of moving a locking ring as above described, may bring intoaction a dog clutch operative to lock the gear in a reverse direction.

Such an arrangement is illustrated in F ig. 6. The ring 70 has noprojecting fingers to enter recesses in the roller cage, and thesynchronizing ring 1 is notched or serrated to form one member of a dogclutch. The part f is extended outwardly beyond the surface f and isprovided with an overhanging notched flange f to form the other memberof a dog .clutch. The ring is is mounted to slide on a key on the hub b.In, the mid position of the ring is, the synchronizing rlng is clear ofpart 7 and also clear of the notched flange F. A cam arrangement similarto s that already described may be employed, the

The improved action of which first causes a braking action to be exertedon the driven member by the synchronizing ring and then causes the ring7' to move over into engagement with the notched flange to lock the gearin a reverse direction. A Bowden cable-controlled spring catch will beprovided as before to permit of release of the do clutch after theclutch pedal has been raised The description above given is that of adevice for use on a motor vehicle with interconnection to the clutchpedal of the vehicle. friction clutch mechanism may, however, be used inother directions.

- Furthermore, the wedge members employed need not necessarily, insuch'cases, be formed with dual cam or inclined surfaces making are-entrant angle with each other as shown.

The requisite angular control movements of the roller cage need notnecessarily be obtained in the manner above described, that is to say bymeans of what I have termed a locking ring.

Having thus described my invention, and in what manner the same is tobevperformed, what I claim as new and desire to secure by Letters Patentis 1. A friction clutch device comprising a driving shaft, a claw membermounted for rotation with said driving shaft and havin a plurality ofpockets therein, a series of we ge members carried in said pockets, anangularly adjustable cage concentric with the claw member, a drivenshaft, an annular drum associated with the driven shaft, rollers carriedby said cage and disposed between said wedge members and the annulardrum, and a central floating ring against which said wedges are adaptedto bear.

2. A friction clutch device comprising a driving shaft, a claw membermounted for rotation with said driving shaft and having a plurality ofpockets therein, a seriesof wedge members carried in said pockets, anangularly adjustable cage concentric with the claw member, a drivenshaft, an annular-drum associated with the driven shaft, rollers carriedby said cage and disposed between said wedge members and the annulardrum, a central floating ring against which said wedges are adapted tobear, and means interconnected with a clutch pedal for effecting angularadrotation with said drivin shaft and having a plurality of pockets terein, a series 'of wedge members carried in said pockets, an angularlyadjustable cage' concentric with the claw member, a driven shaft, anannular drum associated with the driven shaft, rollers carried by saidcage and disposed between said wedge members and the annular drum acentral floating ring against which sai wedges are adapted to bear,means interconnected with a clutch pedal for effecting angularadjustment of said cage, whereby depression, of the clutch pedal willcause the driving and driven shafts to be connected, 9. ring carried bysaid claw member for locking the cage against angular movement, and asynchronizing ring mounted on said locking ring adapted to check thespeed of the driving member before the driving and driven shafts arepositively connected.

4. A friction clutch device comprising a driving shaft, a claw membermounted for rotation with said driving shaft and having a plurality ofpockets therein, a series of wedge members carriedin said pockets, anangularly adjustable cage concentric with said claw member, a drivenshaft, an annular drum associated with the driven shaft, rollers carriedby said cage and disposed between said wedge members and the annulardrum, a central floating ring against which said wedges are adapted tobear, means interconnected with a clutch pedal for effecting angularadjustment of said cage, whereby depression of the clutch pedal willcause the driving and driven shafts to be positively connected, andmeans to maintain the driving connection where the-clutch pedal israised.

In testimony whereof I afli-x my signature.

HENRY EDWARD MERRITT;

justment of said cage, whereby depression of the clutch pedal will causethe driving and driven shafts to be positively connected.

, 3. A friction clutch device comprising .a driving shaft, 8. clawmember mounted for

